/*
 *  Copyright 2007, Google Inc.
 *  Copyright 2012, Intel Inc.
 *
 *  based on omap.c driver, which was
 *  Copyright (C) 2004 Nokia Corporation
 *  Written by Tuukka Tikkanen and Juha Yrjölä <juha.yrjola@nokia.com>
 *  Misc hacks here and there by Tony Lindgren <tony@atomide.com>
 *  Other hacks (DMA, SD, etc) by David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/major.h>

#include <linux/types.h>
#include <linux/pci.h>
#include <linux/interrupt.h>

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/hdreg.h>
#include <linux/kdev_t.h>
#include <linux/blkdev.h>
#include <linux/mutex.h>
#include <linux/scatterlist.h>
#include <linux/mmc/mmc.h>
#include <linux/mmc/sdio.h>
#include <linux/mmc/host.h>
#include <linux/mmc/card.h>

#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <linux/clk.h>
#include <linux/scatterlist.h>

#include <asm/io.h>
#include <asm/irq.h>

#include <asm/types.h>
#include <asm/io.h>
#include <asm/uaccess.h>

#define DRIVER_NAME "goldfish_mmc"

#define BUFFER_SIZE   16384

#define GOLDFISH_MMC_READ(host, addr)   (readl(host->reg_base + addr))
#define GOLDFISH_MMC_WRITE(host, addr, x)   (writel(x, host->reg_base + addr))

enum {
        /* status register */
        MMC_INT_STATUS          = 0x00,
        /* set this to enable IRQ */
        MMC_INT_ENABLE          = 0x04,
        /* set this to specify buffer address */
        MMC_SET_BUFFER          = 0x08,

        /* MMC command number */
        MMC_CMD                 = 0x0C,

        /* MMC argument */
        MMC_ARG                 = 0x10,

        /* MMC response (or R2 bits 0 - 31) */
        MMC_RESP_0                      = 0x14,

        /* MMC R2 response bits 32 - 63 */
        MMC_RESP_1                      = 0x18,

        /* MMC R2 response bits 64 - 95 */
        MMC_RESP_2                      = 0x1C,

        /* MMC R2 response bits 96 - 127 */
        MMC_RESP_3                      = 0x20,

        MMC_BLOCK_LENGTH        = 0x24,
        MMC_BLOCK_COUNT         = 0x28,

        /* MMC state flags */
        MMC_STATE               = 0x2C,

        /* MMC_INT_STATUS bits */

        MMC_STAT_END_OF_CMD     = 1U << 0,
        MMC_STAT_END_OF_DATA    = 1U << 1,
        MMC_STAT_STATE_CHANGE   = 1U << 2,
        MMC_STAT_CMD_TIMEOUT    = 1U << 3,

        /* MMC_STATE bits */
        MMC_STATE_INSERTED     = 1U << 0,
        MMC_STATE_READ_ONLY    = 1U << 1,
};

/*
 * Command types
 */
#define OMAP_MMC_CMDTYPE_BC     0
#define OMAP_MMC_CMDTYPE_BCR    1
#define OMAP_MMC_CMDTYPE_AC     2
#define OMAP_MMC_CMDTYPE_ADTC   3


struct goldfish_mmc_host {
        struct mmc_request      *mrq;
        struct mmc_command      *cmd;
        struct mmc_data         *data;
        struct mmc_host         *mmc;
        struct device           *dev;
        unsigned char           id; /* 16xx chips have 2 MMC blocks */
        void __iomem            *virt_base;
        unsigned int            phys_base;
        int                     irq;
        unsigned char           bus_mode;
        unsigned char           hw_bus_mode;

        unsigned int            sg_len;
        unsigned                dma_done:1;
        unsigned                dma_in_use:1;

        void __iomem            *reg_base;
};

static inline int
goldfish_mmc_cover_is_open(struct goldfish_mmc_host *host)
{
        return 0;
}

static ssize_t
goldfish_mmc_show_cover_switch(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct goldfish_mmc_host *host = dev_get_drvdata(dev);

        return sprintf(buf, "%s\n", goldfish_mmc_cover_is_open(host) ? "open" :
                       "closed");
}

static DEVICE_ATTR(cover_switch, S_IRUGO, goldfish_mmc_show_cover_switch, NULL);

static void
goldfish_mmc_start_command(struct goldfish_mmc_host *host, struct mmc_command *cmd)
{
        u32 cmdreg;
        u32 resptype;
        u32 cmdtype;

        host->cmd = cmd;

        resptype = 0;
        cmdtype = 0;

        /* Our hardware needs to know exact type */
        switch (mmc_resp_type(cmd)) {
        case MMC_RSP_NONE:
                break;
        case MMC_RSP_R1:
        case MMC_RSP_R1B:
                /* resp 1, 1b, 6, 7 */
                resptype = 1;
                break;
        case MMC_RSP_R2:
                resptype = 2;
                break;
        case MMC_RSP_R3:
                resptype = 3;
                break;
        default:
                dev_err(mmc_dev(host->mmc),
                        "Invalid response type: %04x\n", mmc_resp_type(cmd));
                break;
        }

        if (mmc_cmd_type(cmd) == MMC_CMD_ADTC)
                cmdtype = OMAP_MMC_CMDTYPE_ADTC;
        else if (mmc_cmd_type(cmd) == MMC_CMD_BC)
                cmdtype = OMAP_MMC_CMDTYPE_BC;
        else if (mmc_cmd_type(cmd) == MMC_CMD_BCR)
                cmdtype = OMAP_MMC_CMDTYPE_BCR;
        else
                cmdtype = OMAP_MMC_CMDTYPE_AC;

        cmdreg = cmd->opcode | (resptype << 8) | (cmdtype << 12);

        if (host->bus_mode == MMC_BUSMODE_OPENDRAIN)
                cmdreg |= 1 << 6;

        if (cmd->flags & MMC_RSP_BUSY)
                cmdreg |= 1 << 11;

        if (host->data && !(host->data->flags & MMC_DATA_WRITE))
                cmdreg |= 1 << 15;

        GOLDFISH_MMC_WRITE(host, MMC_ARG, cmd->arg);
        GOLDFISH_MMC_WRITE(host, MMC_CMD, cmdreg);
}

static void goldfish_mmc_xfer_done(struct goldfish_mmc_host *host,
                                   struct mmc_data *data)
{
        if (host->dma_in_use) {
                enum dma_data_direction dma_data_dir;

                if (data->flags & MMC_DATA_WRITE)
                        dma_data_dir = DMA_TO_DEVICE;
                else
                        dma_data_dir = DMA_FROM_DEVICE;

                if (dma_data_dir == DMA_FROM_DEVICE) {
                        /*
                         * We don't really have DMA, so we need
                         * to copy from our platform driver buffer
                         */
                        uint8_t *dest = (uint8_t *)sg_virt(data->sg);
                        memcpy(dest, host->virt_base, data->sg->length);
                }
                host->data->bytes_xfered += data->sg->length;
                dma_unmap_sg(mmc_dev(host->mmc), data->sg, host->sg_len,
                             dma_data_dir);
        }

        host->data = NULL;
        host->sg_len = 0;

        /*
         * NOTE:  MMC layer will sometimes poll-wait CMD13 next, issuing
         * dozens of requests until the card finishes writing data.
         * It'd be cheaper to just wait till an EOFB interrupt arrives...
         */

        if (!data->stop) {
                host->mrq = NULL;
                mmc_request_done(host->mmc, data->mrq);
                return;
        }

        goldfish_mmc_start_command(host, data->stop);
}

static void goldfish_mmc_end_of_data(struct goldfish_mmc_host *host,
                                     struct mmc_data *data)
{
        if (!host->dma_in_use) {
                goldfish_mmc_xfer_done(host, data);
                return;
        }
        if (host->dma_done)
                goldfish_mmc_xfer_done(host, data);
}

static void goldfish_mmc_cmd_done(struct goldfish_mmc_host *host,
                                  struct mmc_command *cmd)
{
        host->cmd = NULL;
        if (cmd->flags & MMC_RSP_PRESENT) {
                if (cmd->flags & MMC_RSP_136) {
                        /* response type 2 */
                        cmd->resp[3] =
                                GOLDFISH_MMC_READ(host, MMC_RESP_0);
                        cmd->resp[2] =
                                GOLDFISH_MMC_READ(host, MMC_RESP_1);
                        cmd->resp[1] =
                                GOLDFISH_MMC_READ(host, MMC_RESP_2);
                        cmd->resp[0] =
                                GOLDFISH_MMC_READ(host, MMC_RESP_3);
                } else {
                        /* response types 1, 1b, 3, 4, 5, 6 */
                        cmd->resp[0] =
                                GOLDFISH_MMC_READ(host, MMC_RESP_0);
                }
        }

        if (host->data == NULL || cmd->error) {
                host->mrq = NULL;
                mmc_request_done(host->mmc, cmd->mrq);
        }
}

static irqreturn_t goldfish_mmc_irq(int irq, void *dev_id)
{
        struct goldfish_mmc_host *host = (struct goldfish_mmc_host *)dev_id;
        u16 status;
        int end_command = 0;
        int end_transfer = 0;
        int transfer_error = 0;
        int state_changed = 0;
        int cmd_timeout = 0;

        while ((status = GOLDFISH_MMC_READ(host, MMC_INT_STATUS)) != 0) {
                GOLDFISH_MMC_WRITE(host, MMC_INT_STATUS, status);

                if (status & MMC_STAT_END_OF_CMD)
                        end_command = 1;

                if (status & MMC_STAT_END_OF_DATA)
                        end_transfer = 1;

                if (status & MMC_STAT_STATE_CHANGE)
                        state_changed = 1;

                if (status & MMC_STAT_CMD_TIMEOUT) {
                        end_command = 0;
                        cmd_timeout = 1;
                }
        }

        if (cmd_timeout) {
                struct mmc_request *mrq = host->mrq;
                mrq->cmd->error = -ETIMEDOUT;
                host->mrq = NULL;
                mmc_request_done(host->mmc, mrq);
        }

        if (end_command)
                goldfish_mmc_cmd_done(host, host->cmd);

        if (transfer_error)
                goldfish_mmc_xfer_done(host, host->data);
        else if (end_transfer) {
                host->dma_done = 1;
                goldfish_mmc_end_of_data(host, host->data);
        } else if (host->data != NULL) {
                /*
                 * WORKAROUND -- after porting this driver from 2.6 to 3.4,
                 * during device initialization, cases where host->data is
                 * non-null but end_transfer is false would occur. Doing
                 * nothing in such cases results in no further interrupts,
                 * and initialization failure.
                 * TODO -- find the real cause.
                 */
                host->dma_done = 1;
                goldfish_mmc_end_of_data(host, host->data);
        }

        if (state_changed) {
                u32 state = GOLDFISH_MMC_READ(host, MMC_STATE);
                pr_info("%s: Card detect now %d\n", __func__,
                        (state & MMC_STATE_INSERTED));
                mmc_detect_change(host->mmc, 0);
        }

        if (!end_command && !end_transfer &&
            !transfer_error && !state_changed && !cmd_timeout) {
                status = GOLDFISH_MMC_READ(host, MMC_INT_STATUS);
                dev_info(mmc_dev(host->mmc),"spurious irq 0x%04x\n", status);
                if (status != 0) {
                        GOLDFISH_MMC_WRITE(host, MMC_INT_STATUS, status);
                        GOLDFISH_MMC_WRITE(host, MMC_INT_ENABLE, 0);
                }
        }

        return IRQ_HANDLED;
}

static void goldfish_mmc_prepare_data(struct goldfish_mmc_host *host,
                                      struct mmc_request *req)
{
        struct mmc_data *data = req->data;
        int block_size;
        unsigned sg_len;
        enum dma_data_direction dma_data_dir;

        host->data = data;
        if (data == NULL) {
                GOLDFISH_MMC_WRITE(host, MMC_BLOCK_LENGTH, 0);
                GOLDFISH_MMC_WRITE(host, MMC_BLOCK_COUNT, 0);
                host->dma_in_use = 0;
                return;
        }

        block_size = data->blksz;

        GOLDFISH_MMC_WRITE(host, MMC_BLOCK_COUNT, data->blocks - 1);
        GOLDFISH_MMC_WRITE(host, MMC_BLOCK_LENGTH, block_size - 1);

        /*
         * Cope with calling layer confusion; it issues "single
         * block" writes using multi-block scatterlists.
         */
        sg_len = (data->blocks == 1) ? 1 : data->sg_len;

        if (data->flags & MMC_DATA_WRITE)
                dma_data_dir = DMA_TO_DEVICE;
        else
                dma_data_dir = DMA_FROM_DEVICE;

        host->sg_len = dma_map_sg(mmc_dev(host->mmc), data->sg,
                                  sg_len, dma_data_dir);
        host->dma_done = 0;
        host->dma_in_use = 1;

        if (dma_data_dir == DMA_TO_DEVICE) {
                /*
                 * We don't really have DMA, so we need to copy to our
                 * platform driver buffer
                 */
                const uint8_t *src = (uint8_t *)sg_virt(data->sg);
                memcpy(host->virt_base, src, data->sg->length);
        }
}

static void goldfish_mmc_request(struct mmc_host *mmc, struct mmc_request *req)
{
        struct goldfish_mmc_host *host = mmc_priv(mmc);

        WARN_ON(host->mrq != NULL);

        host->mrq = req;
        goldfish_mmc_prepare_data(host, req);
        goldfish_mmc_start_command(host, req->cmd);

        /*
         * This is to avoid accidentally being detected as an SDIO card
         * in mmc_attach_sdio().
         */
        if (req->cmd->opcode == SD_IO_SEND_OP_COND &&
            req->cmd->flags == (MMC_RSP_SPI_R4 | MMC_RSP_R4 | MMC_CMD_BCR))
                req->cmd->error = -EINVAL;
}

static void goldfish_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
        struct goldfish_mmc_host *host = mmc_priv(mmc);

        host->bus_mode = ios->bus_mode;
        host->hw_bus_mode = host->bus_mode;
}

static int goldfish_mmc_get_ro(struct mmc_host *mmc)
{
        uint32_t state;
        struct goldfish_mmc_host *host = mmc_priv(mmc);

        state = GOLDFISH_MMC_READ(host, MMC_STATE);
        return ((state & MMC_STATE_READ_ONLY) != 0);
}

static const struct mmc_host_ops goldfish_mmc_ops = {
        .request        = goldfish_mmc_request,
        .set_ios        = goldfish_mmc_set_ios,
        .get_ro         = goldfish_mmc_get_ro,
};

static int goldfish_mmc_probe(struct platform_device *pdev)
{
        struct mmc_host *mmc;
        struct goldfish_mmc_host *host = NULL;
        struct resource *res;
        int ret = 0;
        int irq;
        dma_addr_t buf_addr;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        irq = platform_get_irq(pdev, 0);
        if (res == NULL || irq < 0)
                return -ENXIO;

        mmc = mmc_alloc_host(sizeof(struct goldfish_mmc_host), &pdev->dev);
        if (mmc == NULL) {
                ret = -ENOMEM;
                goto err_alloc_host_failed;
        }

        host = mmc_priv(mmc);
        host->mmc = mmc;

        pr_err("mmc: Mapping %lX to %lX\n", (long)res->start, (long)res->end);
        host->reg_base = ioremap(res->start, resource_size(res));
        if (host->reg_base == NULL) {
                ret = -ENOMEM;
                goto ioremap_failed;
        }
        host->virt_base = dma_alloc_coherent(&pdev->dev, BUFFER_SIZE,
                                             &buf_addr, GFP_KERNEL);

        if (host->virt_base == 0) {
                ret = -ENOMEM;
                goto dma_alloc_failed;
        }
        host->phys_base = buf_addr;

        host->id = pdev->id;
        host->irq = irq;

        mmc->ops = &goldfish_mmc_ops;
        mmc->f_min = 400000;
        mmc->f_max = 24000000;
        mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
        mmc->caps = MMC_CAP_4_BIT_DATA;

        /* Use scatterlist DMA to reduce per-transfer costs.
         * NOTE max_seg_size assumption that small blocks aren't
         * normally used (except e.g. for reading SD registers).
         */
        mmc->max_segs = 32;
        mmc->max_blk_size = 2048;       /* MMC_BLOCK_LENGTH is 11 bits (+1) */
        mmc->max_blk_count = 2048;      /* MMC_BLOCK_COUNT is 11 bits (+1) */
        mmc->max_req_size = BUFFER_SIZE;
        mmc->max_seg_size = mmc->max_req_size;

        ret = request_irq(host->irq, goldfish_mmc_irq, 0, DRIVER_NAME, host);
        if (ret) {
                dev_err(&pdev->dev, "Failed IRQ Adding goldfish MMC\n");
                goto err_request_irq_failed;
        }

        host->dev = &pdev->dev;
        platform_set_drvdata(pdev, host);

        ret = device_create_file(&pdev->dev, &dev_attr_cover_switch);
        if (ret)
                dev_warn(mmc_dev(host->mmc),
                         "Unable to create sysfs attributes\n");

        GOLDFISH_MMC_WRITE(host, MMC_SET_BUFFER, host->phys_base);
        GOLDFISH_MMC_WRITE(host, MMC_INT_ENABLE,
                           MMC_STAT_END_OF_CMD | MMC_STAT_END_OF_DATA |
                           MMC_STAT_STATE_CHANGE | MMC_STAT_CMD_TIMEOUT);

        mmc_add_host(mmc);
        return 0;

err_request_irq_failed:
        dma_free_coherent(&pdev->dev, BUFFER_SIZE, host->virt_base,
                          host->phys_base);
dma_alloc_failed:
        iounmap(host->reg_base);
ioremap_failed:
        mmc_free_host(host->mmc);
err_alloc_host_failed:
        return ret;
}

static int goldfish_mmc_remove(struct platform_device *pdev)
{
        struct goldfish_mmc_host *host = platform_get_drvdata(pdev);

        BUG_ON(host == NULL);

        mmc_remove_host(host->mmc);
        free_irq(host->irq, host);
        dma_free_coherent(&pdev->dev, BUFFER_SIZE, host->virt_base, host->phys_base);
        iounmap(host->reg_base);
        mmc_free_host(host->mmc);
        return 0;
}

static struct platform_driver goldfish_mmc_driver = {
        .probe          = goldfish_mmc_probe,
        .remove         = goldfish_mmc_remove,
        .driver         = {
                .name   = DRIVER_NAME,
        },
};

module_platform_driver(goldfish_mmc_driver);
MODULE_LICENSE("GPL v2");